When I attemp to run Illustrator on my machine running Windows 8.1 preview I see this error message (In spanish because both my system and software language are in spanish):
Error
Esta aplicación no es compatible con el idioma del sistema operativo actual. Abra el Panel de control "Opciones regionales y de idioma" en el menú Inicio de Windows.
This application is not compatible with the curren operating system language. Open Region and settings in Control panel on Windows Start menu.
I tried switching to Spanish (Spain), Spanish (United Stated), English (United States) and back to Spanish (Chile) with no results.